A. Field of Invention
This invention pertains to an apparatus for performing phacoemulsification using a handpiece including a hollow needle used to pulverize the lens and a sleeve surrounding the needle. Irrigating liquid is injected into the anterior chamber from the sleeve. The sleeve is provided with a plurality of bumpers arranged to minimize deflections of the needle during the emulsification process thereby minimizing obstruction of infusion fluid from the exit ports in the sleeve.
B. Description of the Prior Art
Phaco-emulsification is a procedure used to break up and remove the natural lens from the capsular bag within the eye of a person. Most often the procedure is used as a means of treating a person having cataracts. The procedure involves making a small incision in the eye and introducing through the incision a thin hollow needle having a central passage. A circumferential sleeve surrounds the needle. The needle is coupled to an ultrasonic generator that vibrates the needle in a predetermined (preferably ultrasonic) frequency range causing the natural lens to fragment and emulsify. Irrigation fluid enters the anterior chamber of the eye through two or more ports formed in the outer sleeve surrounding the needle. Detritus resulting from the phaco-emulsification process mixes together with the liquid and is aspired through the central passage in the needle. The liquid used for irrigation also produces a stabilizing effect in the anterior and posterior chambers, keeping the eye inflated.
To complete the operation, an intraocular lens implant is then inserted into the capsular bag (usually through the same incision).
While the technology has for the most part been broadly accepted as the community norm, the present inventor has discovered several disadvantages in the presently available equipment used for phaco-emulsification. It is preferable to have the liquid used for irrigation ejected evenly from ports to insure a relatively smooth, non-turbulent and non-violent fluid flow within the anterior chamber. However the present inventor has discovered that during phaco-emulsification, the needle deflects considerably within the sleeve frequently occludes or blocks one of the ports on the sleeve (at least partially). As a result, since the pressure within the sleeve is fairly constant, the flow of the liquid through one of the ports is reduced temporarily by the deflected needle, the flow through the other port(s) increases suddenly, In other words, while one port is at least partially blocked by the needle, the liquid through the other port is ejected at a greater volume and velocity. This effect is undesirable since it can cause detritus resulting from the phaco-emulsification to be pushed away from the aspiration tip and toward the furthest corners of the anterior chamber, occasionally transporting unwanted lens material to the back of the eye. Additional problems may also occur as a result of uneven liquid flow through the ports. The present invention addresses this problem. It should be understood that during emulsification, the needle deflection changes continuously during emulsification, and it blocks one of the ports only for fractions of a second—often alternating rapidly from one side of the sleeve to the other.